【线段树 && 区间增减】POJ 3468 A Simple Problem with Integers

Problem Description

裸的区间增减的题目，由于数据有点大，得用long long。输入n,m 有n个元素，m次询问。C a b c 将区间a-b的数全部加c，Q a b，求区间a-b的和

代码：

#include<cstdio>
using namespace std;
struct node
{
    long long num, lazy;
};
node tree[];
#define MID int mid = (l + r) / 2
//预处理
#define lson root<<1
#define rson root<<1|1
node merge_(node x, node y)
//回潮求和
{
    node t;
    t.lazy = ;
//因为这里没有初始化，wrong了 好多遍
    t.num = x.num + y.num;
    return t;
}
void build(int root, int l, int r)
//初始化线段树
{
    tree[root].lazy = ;
//初始化0
    if(l == r)
    {
        scanf("%lld", &tree[root].num);
//输入
        return ;
    }
    MID;
    build(lson, l, mid);
//左子树递归
    build(rson, mid + , r);
//右子树递归
    tree[root] = merge_(tree[lson], tree[rson]);
}
void pushdown(int root, int l, int r)
//向下更新
{
    if(tree[root].lazy) {//如果lazy有值的话
    tree[lson].lazy += tree[root].lazy;
//左孩子lazy 值更新
    tree[rson].lazy += tree[root].lazy;
//右孩子lazy 值更新
    MID;
    tree[lson].num += (mid - l + ) * tree[root].lazy;//更新和
    tree[rson].num += (r - (mid + ) + ) * tree[root].lazy;
//更新和
    tree[root].lazy = ;
//变为0
    }
}
void updata(int root, int l, int r, int ul, int ur, long long v)
//区间ul-ur增加v
{
    if(ul <= l && r <= ur)
//在区间内
    {
        tree[root].lazy += v;
        tree[root].num += (r - l + ) * v;
        return ;
    }
    pushdown(root, l, r);
//向下更新lazy
    MID;
    if(mid >= ul) updata(lson, l, mid, ul, ur, v);
//递归
    if(mid < ur) updata(rson, mid + , r, ul, ur, v);
//递归
    tree[root] = merge_(tree[lson], tree[rson]);
//归并
}
long long query(int root, int l, int r, int ul, int ur)
//求ul-ur的和
{
    if(ul <= l && r <= ur)
//在区间内返回值
    {
        return tree[root].num;
    }
    pushdown(root, l, r);
    MID;
    long long red = ;
    if(mid >= ul) red = query(lson, l, mid, ul, ur);
//mid 在 左孩子区间
    if(mid < ur) ryou query(rson, mid + , r, ul, ur);
//mid 在 右孩子区间
    return red;
}
int main()
{
    int n, m, L, R;
    long long v;
    char c;
    while(~scanf("%d %d", &n, &m))
    {
        build(, , n);
        while(m--)
        {
            scanf("%*c%c", &c);
            if(c == 'Q')
            {
                scanf("%d %d", &L, &R);
                printf("%lld\n", query(, , n, L, R));
            }
            else
            {
                scanf("%d %d %lld", &L, &R, &v);
                updata(, , n, L, R, v);
            }
        }
    }
    return ;
}